Inheritance analysis of the main economic characters of apricot

Abstract：【Objective】It was found that lack of good varieties with strong flavor and long storage life is one of the important factors restricting the development of apricot industry. Therefore, the Liaoning Institute of Pomology initiated the target breeding program to select apricot varieties with high eating quality, good storage life and attractive appearance. The inheritance trends of main economic characters of apricot was investigated using hybrid populations to provide the theoretical basis for selecting parents and formulating breeding strategy.【Methods】The F1 segregation progenies of 3 crossing combinations were used as materials, including 56, 50, and 89 individual seedlings derived from‘Sungold'בShajinhong',‘Saimaiti'בSungold'and‘Sungold'בJipin', respectively. The seedling trees were planted in the field in 2009, 2009 and 2010, respectively. The phenotypes of 10 major economic traits were investigated to analyze the inheritance tendencies, including blooming data, fruit ripening time,fruit weight, flesh type, flesh firmness, soluble solid content, fruit aroma, cling/free stone, yielding ability, and kernel flavor in 2016, 2017, and 2018. The ripening time was recorded by the number of days after the first day of the year(January 1 as the first day), and the blooming date was determined when50% of the flowers of the whole tree were fully open. The fruit ripeing date was recorded when about75% of the fruits changed color and the flesh was elastic with typical flavor. Chi-square test was used to determine the population segregation ratios of flesh type, cling or free stone, fruit aroma, and kernel flavor of apricot. The heritability and coefficient of variation (CV) were calculated for fruit weight, fruit firmness, and soluble solids content. All the data were processed by SPSS 22.0 statistical analysis software. The flowering date and ripening date were plotted by Origin 9.5.【Results】The distribution range of the flowering period of apricot was narrow, lasting only two to four days and the average flowering date of the hybrid progenies tended to the value of the mid-parents. Transgressive segregation was found on flowering date and fruit maturity date in all three combinations. The distribution range of CV of the ripening period was significantly wider than that of the flowering period. The variations exhibited a normal or skewed distribution trend to the late-maturing parents. The average fruit weight of each hybrid progeny was lower than the value of the mid-parents, and the distribution range tended to small fruits, showing a significant declining trend but a high CV(31.4%-36.9%). The average flesh firmness value of each hybrid progeny was lower than the value of the mid-parents and the ratios of over highparent were low, they were 1.1%, 12.5%, and 3.9%, respectively, while the ratios of over lower-parent were high, they were 30.3%, 39.3%, and 92.2%, respectively. The offspring showed a continuous variation trend to the soft flesh of parents. The soluble solids content(SSC) showed a continuous variation with low CV and low proportion of over high-parent, but high heritability(0.91-0.92), indicating that the ability of parents to inherit high-SSC trait to their progenies was strong. The yielding ability of hybrid progenies showed a continuous variation trend to the high-yield parents, and the yielding ability of the parents had a great influence on their progenies. Flesh type(hard-melting or soft-melting), stone adhere to flesh(free or clinging), fruit aroma(aroma or aroma-free), and kernel flavor of apricot(sweet or bitter) were quality traits. The flesh type was almost hard-melting in F1 progenies of‘Sungold'בShajinhong'and‘Saimaiti'בSungold', the hard-melting/soft-melting ratio fitted on the 1∶1 segregation for F1 progenies of‘Sungold'בJipin'. Among the four hybrid parents, only‘Jinpin'was aromatic,and the aroma/aroma-free ratio fitted on the 1:1 segregation for F1 progenies of‘Sungold'בJipin'. The freestone trait was dominant in the progenies of all the combinations, the free/clinging ratio fitted on the3∶1 segregation for‘Sungold'בJipin'. The sweet kernel flavor of apricot was controlled by a single dominant gene.‘Saimaiti',‘Shajinhong', and‘Sungold'were classified as homozygously dominant,heterozygous, and homozygously recessive, respectively.【Conclusion】‘Sungold'would be a promising parent due to the strong heritability for some main economic traits.